Stroke is one of the leading causes of death and a top cause of serious long-term disability. A number of stroke risk factors have been established at the individual-level; however, these risk factors only partially explain stroke risk and account for only half of the racial disparities in stroke. Novel exposures of stroke risk must be identifie to improve our understanding of stroke risk and to develop effective interventions. Recently, built and social environments (BSEs) have been identified as important factors to examine to further our understanding of cardiovascular disease. However, to date no studies have examined the effect of BSEs on stroke risk. BSEs may also help to explain the large racial and geographic disparities in stroke rates although this has yet to be empirically examined nationally. The proposed study would address these gaps by utilizing a unique assembled cohort, namely the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort. The REGARDS cohort is a national sample of adults over age 45, with oversamples of African-American participants and persons in the stroke belt. The proposed study will expand the REGARDS study to examine the effects of BSEs on incident stroke risk and on racial and geographic disparities in stroke. These aims will be achieved by obtaining data on a broad range of BSE characteristics of the REGARDS participants' built environment (e.g., food availability, park availability, food prices, physical activity facility availability, land use, steet connectivity and neighborhood physical environment) and participants' social environment (objective crime, perceived crime, neighborhood SES, social cohesion, racial residential segregation, social support and social networks, and neighborhood social environment). The data will be obtained from a number of sources including secondary commercial and administrative sources, participant self-reports and primary audits using the Street View feature in Google Earth. Environmental data will be spatially linked to participant data of the REGARDS case-cohort study. The proposed study aims to 1) examine the extent to which BSEs contribute to incident stroke risk in the REGARDS study; and 2) determine the extent to which BSEs explain racial and geographic disparities in incident stroke. The proposed study builds on important preliminary studies and the extensive relevant experience of the investigative team, which includes prominent scholars across a number of institutions. The proposed research provides a cost-effective way to examine the importance of BSEs for stroke prevention across diverse community settings and racial groups. Identifying the BSE characteristics that are predictive of incident stroke and BSEs that contribute to racial and geographic disparities will help inform future modifications of environments to improve population health. At the end of the study period, the BSE data will be made available to others through the REGARDS data sharing protocols; thus the measures in the proposed study will be available to the greater scientific community for use in research pertaining to other disease outcomes.